docs: def join(self, sequence):
          """Return concatenation of bitstrings joined by self.
  
          sequence -- A sequence of bitstrings.
  
          """
          s = self.__class__()
          i = iter(sequence)
          try:
              s._append(Bits(next(i)))
              while True:
                  n = next(i)
                  s._append(self)
                  s._append(Bits(n))
          except StopIteration:
              pass
          return s